The Dentist Is Pleased If, and Only If, I Both

Multiple Choice

The dentist is pleased if, and only if, I both brush and floss. The dentist is not pleased, but I brush. So, I don't floss.
-Which of the following propositions is an immediate (one-step) consequence in PL of the given premises?

A) ∼P ≡ (B • F)
B) ∼P ≡ ∼(B • F)
C) ∼[P ≡ (B • F) ]
D) ∼(B • F) ≡ P
E) None of the above